Heat Transfer Theory
Oil Sensible Heat Duty
The sensible heat duty for the oil phase is:
where Q0 = oil flow rate, bpd
SG = oil specific gravity
C0 = oil specific heat, Btu/lb-°F (Figure 2-13)
T1 = initial temperature, °F
T2 = final temperature, °F
Natural Gas Sensible Heat Duty at Constant Pressure
The sensible heat duty for natural gas at constant pressure is:
Heat capacity is determined at atmospheric conditions and then corrected for temperature and pressure based on reduced pressure and temperature.
The gas pseudo critical pressures and temperatures can be approximated from Figure 2-16 or they can be calculated as weighted averages of the critical temperatures and [...]
12Sep2009 | admin | Comments Off | ContinuedHeat Duty for Multiphase Streams
When a process stream consists of more than one phase, the process heat duty can be calculated using the following equation:
12Sep2009 | admin | Comments Off | ContinuedLatent Heat
The amount of heat energy absorbed or lost by a substance when changing phases is called “latent heat.” When steam is condensed towater, the temperature doesn’t change, but heat must be extracted from
the steam as it goes through a phase change to water. To change water to steam, heat must be added. When a substance [...]
Sensible Heat
The amount of heat absorbed or lost by a substance that causes a change in the temperature of the substance is sensible heat. It is called sensible heat because it can be measured by the change in temperature it causes. For example, as heat is added to a piece of steel the temperature of that [...]
12Sep2009 | admin | Comments Off | ContinuedApproximate Overall Heat Transfer Coefficient
The calculation of overall heat transfer coefficient U using the equations previously presented can be rather tedious. Heat transfer specialists have computer programs to calculate this value. There are some quick approximation techniques. Table 2-8 comes from the Gas Processors Suppliers Association’s Engineering Data Book and gives an approximate value of U for shell and [...]
9Sep2009 | admin | Comments Off | ContinuedOutside Film Coefficient (Shell-and-Tube Exchangers)
For shell-and-tube heat exchangers with shell-side baffles, the shellside fluid flow is perpendicular to the tubes. In this arrangement, the outside film coefficient can be calculated from the following equation:
9Sep2009 | admin | Comments Off | Continued